Plasticizer Composition Containing Cyclodextrin Derivatives, Flexible PVC Composition With Suppression of the Migration of Plasticizer Containing the Same, and Manufacturing Method Thereof

ABSTRACT

Disclosed are plasticizer compositions including cyclodextrin derivatives, a flexible PVC composition with suppression of the migration of a plasticizer containing the same, and a manufacturing method thereof. The manufacturing method of the flexible PVC composition of the present invention includes steps of (S1) preparing cyclodextrin derivatives; (S2) mixing the cyclodextrin derivatives, PVC and a low molecular weight liquid plasticizer to form a plastisol; and (S3) heating the plastisol to form a solution and cooling the solution. The manufacturing method of the present invention may be useful to mass-produce flexible PVC with suppression of the migration of a plasticizer in a simple and economic manner without using solvents since the cyclodextrin derivatives are used as a compound that can suppress the migration of a plasticizer The flexible PVC has an effect of reducing an amount of the migrated plasticizer without deterioration in its physical properties.

TECHNICAL FIELD

The present invention relates to a method for manufacturing a flexiblePVC composition prepared by mixing PVC with a low molecular weightliquid plasticizer, and more particularly to a plasticizer compositioncapable of suppressing the migration of a plasticizer since a lowmolecular weight liquid plasticizer is mixed with a cyclodextrinderivative to form a complex, a method for manufacturing a flexible PVCcomposition with suppression of the migration of a plasticizercontaining the same, and a flexible PVC composition with suppression ofthe migration of a plasticizer formed therefrom.

BACKGROUND ART

For example, PVC is a typical polymer that has been widely used forpipes for piping systems, food packaging materials, textile fibers, homedecorations, blood storage containers, and infant articles such asnursing bottles, toys, etc. However, PVC has certain hardness due to thelimit of its molecular mobility since a unique hierarchy structure andmicrocrystallite are present in the PVC, the microcrystallite playing arole in its physical crosslinks. Therefore, a flexible characteristicshould be given to the PVC by means of a plasticization process in orderto apply to flexible products such as food package films. A flexible PVCis generally manufactured by mixing a low molecular weight liquidplasticizer with PVC to form a plastisol, followed by heating theresultant plastisol to dissolve the PVC into the low molecular weightliquid plasticizer and cooling the plastisol. A phthalate plasticizer, aphosphate plasticizer, a trimellitate plasticizer, an aliphatic diesterplasticizer, etc. has been widely known as the low molecular weightliquid plasticizer, and there are also an epoxy plasticizer, ananti-chlorine plasticizer, etc in addition to the above plasticizers.The flexibility is given to the PVC since its molecular mobility issignificantly improved when a low molecular weight liquid plasticizer isadded to the PVC.

As described above, the low molecular weight liquid plasticizer may veryeffectively used for softening PVC, but has characteristics that it isvolatile in the air due to inherent characteristics of low molecularweight liquid materials, or it is transferred to the outside of the PVCwhen it is in contact with liquid or solid materials. It has beenreported that the plasticizer migrated to the outside of the PVC is veryharmful to the plants and the animals since it inhibits the normalactivity of the endocrine system which is directly involved in theirlife activities or induces the abnormal activity of the endocrine systemwhen the plasticizer is permeated into the bodies of plants and animalsincluding human beings.

Accordingly, there have been continuous attempts to suppress themigration of a plasticizer.

For example, there have been attempts to substitute a low molecularweight liquid plasticizer with a high molecular weight plasticizer inorder to solve the migration of plasticizers from PVC products. However,the problem is that, when the high molecular weight plasticizer is usedin the PVC products, its economic efficiency is low or its plasticperformance is not sufficient, and the chain entanglement appears in thehigh molecular weight plasticizer.

Meanwhile, it has been reported that cyclodextrin may contribute tosuppressing the migration of plasticizers from flexible PVC since thecyclodextrin forms a complex with a low molecular weight liquidplasticizer such as DOP, as disclosed in Journal of Applied PolymerScience, 1996, Vol. 59, P. 2089 “Effect of blending β-cyclodextrin withpoly (vinyl chloride) on the leaching of phthalate ester to hydrophilicmedium”.

As shown in α-cyclodextrin of the following Formula 1, the cyclodextrinis a cyclic compound composed of glucose groups as a repeating unit, andrepresented by the following Formula 2.

wherein, “n” represents the number of the repeating units of glucosegroups, and is an integer from 6 to 26, and preferably from 6 to 8.

The cyclodextrin has a unique structure composed of an outer partsurrounded by hydrophilic hydroxy functional groups; and a hydrophobiccavity. The cyclodextrin may form a complex with a plasticizer having asuitable size for entering the cavity, namely a low molecular weightliquid plasticizer. In addition that the cyclodextrin derivativesattract the low molecular weight liquid plasticizer into their cavities,the cyclodextrin derivatives also attract and fix the low molecularweight liquid plasticizer by means of hydrogen bonds, etc.

However, if the cyclodextrin is mixed with the PVC and the low molecularweight liquid plasticizer, they cohere to each other due to lowdispersibility, and therefore an effect on the suppression of themigration of the plasticizer is significantly poor, and physicalproperties of the manufactured flexible PVC are also deteriorated. Inorder to solve the problems, a flexible PVC with suppression of themigration of a plasticizer was manufactured using a method includingsteps of dispersing PVC, DOP and cyclodextrin in a dimethylacetamide(DMAc) solvent and casting the resultant mixture, as disclosed in theabove literature. However, the method has also problems that itseconomic efficiency is low and it is difficult to mass-produce PVCproducts, as well as the cohesion of the cyclodextrin is not completelysolved.

DISCLOSURE OF INVENTION

Accordingly, the present invention is designed to solve the problems ofthe prior art, and therefore it is an object of the present invention toprovide a method for manufacturing a flexible PVC composition withsuppression of the migration of a plasticizer, the flexible PVCcomposition being capable of mass-producing a flexible PVC in a simpleand economic manner without using solvents and highly suppressing themigration of a plasticizer without deterioration in physical propertiesof the manufactured flexible PVC.

It is another object of the present invention to provide a plasticizercomposition capable of suppressing the migration of a plasticizerwithout deterioration in physical properties of the composition since alow molecular weight liquid plasticizer is mixed with a cyclodextrinderivative to form a complex, and a flexible PVC composition withsuppression of the migration of a plasticizer containing the same.

In order to accomplish the above object, the present invention providesa method for manufacturing a flexible PVC composition with suppressionof the migration of a plasticizer, the method including:

(S1) preparing cyclodextrin derivatives represented by the followingFormula 3;

(S2) mixing the cyclodextrin derivatives, PVC and a low molecular weightliquid plasticizer to form a plastisol; and

(S3) heating the formed plastisol to form a solution and cooling thesolution:

wherein, R is independently selected from the group consisting ofhydrogen, a hydrocarbon functional group having 1 to 20 carbon atomsrepresented by the following Formula 4, and a silane functional grouphaving 1 to 60 carbon atoms represented by the following Formula 5,where the substituent “R” has a substitution degree of 5 to 100%; and

n is an integer from 6 to 26:

and

wherein, a, b, c, d and e are each an integer having a value of at least0, where the sum of a+b+c+d+e is at least 1, and the linking order ofthe constituent units a, b, c, d and e is randomly changed:

wherein, R₁, R₂ and R₃ are each independently a hydrocarbon functionalgroup having 1 to 20 carbon atoms represented by the Formula 4.

According to the manufacturing method of the present invention, theflexible PVC with suppression of the migration of a plasticizer may bemass-produced in a simple and economic manner without using solvents,and the migration of the plasticizer may be highly suppressed withoutdeterioration in physical properties of the manufactured flexible PVC.

In the method for manufacturing a flexible PVC composition withsuppression of the migration of a plasticizer according to the presentinvention, the cyclodextrin derivatives preferably have a content of 2to 20 mol, based on 100 mol of the low molecular weight liquidplasticizer.

In the method for manufacturing a flexible PVC composition withsuppression of the migration of a plasticizer according to the presentinvention, the low molecular weight liquid plasticizer includesphthalate plasticizers such as dimethyl phthalate (DMP), dibutylphthalate (DBP), di-isobutyl phthalate (DIBP), dihexyl phthalate (DHP),dioctyl phthalate (DOP), di-iso-octyl phthalate (DIOP), dinonylphthalate (DNP), di-isodecyl phthalate (DIDP), benzyl butyl phthalate(BBP), etc.; aliphatic diester plasticizers such as dioctyl adipate(DOA), di-iso-octyl adipate (DIOA), di-isodecyl adipate (DIDA), etc.;trimellitate plasticizers such as tri-iso-octyl trimellitate (TIOTM),etc.; and phosphate plasticizers such as tritolyl phosphate (TTP),trixylyl phosphate (TXP), etc., and they may be used alone or incombinations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a structure of α-cyclodextrinderivatives as one example of cyclodextrin derivatives used in thepresent invention.

FIG. 2 is a schematic diagram showing a structure of a cyclodextrinderivative which attracts DOP into its cavity to form a complex in aplasticizer composition of the present invention.

FIG. 3 is a schematic diagram showing a structure of a flexible PVCcomposition with suppression of the migration of a plasticizer in whichPVC, a low molecular weight liquid plasticizer and cyclodextrinderivatives are mixed homogeneously with each other according to thepresent invention.

FIG. 4 is a photograph taken of a surface of a cyclodextrinderivatives-free sample (PVC-0) of Comparative example 1.

FIG. 5 is a photograph taken of a surface of a sample (PVC-9) of Example4 containing a small amount of the cyclodextrin derivatives.

FIG. 6 is a photograph taken of a surface of a sample obtained bydispersing pure β-cyclodextrin in a DMAc solvent according to the priorart.

FIG. 7 is an absorbance calibration curve of a standard solutionprepared to determine a concentration of a migrated phthalateplasticizer.

FIG. 8 is a graph showing results of DOP migration tests of PVC sampleswith suppression of the migration of a plasticizer according to thepresent invention.

FIG. 9 is a graph showing stress-strain curves of flexible PVC sampleswith suppression of the migration of a plasticizer according to thepresent invention.

BEST MODES FOR CARRYING OUT THE INVENTION

Hereinafter, a method for manufacturing a flexible PVC composition withsuppression of the migration of a plasticizer according to the presentinvention will be described in detail with reference to the accompanyingdrawings.

Firstly, cyclodextrin derivatives represented by the following Formula 3are prepared (S1).

In the Formula 3, R may be independently hydrogen, a hydrocarbonfunctional group having 1 to 20 carbon atoms represented by thefollowing Formula 4, or a silane functional group having 1 to 60 carbonatoms represented by the following Formula 5. n is an integer from 6 to26, and preferably from 6 to 8. The substituent “R” has a substitutiondegree of 5 to 100%, and preferably from 20 to 90%, and the substitutiondegree is calculated according to the following Equation 1, as follows.

$\begin{matrix}{{{{Substitution}\mspace{14mu} {Degree}} = {\left( \frac{\begin{matrix}\begin{matrix}{{Total}\mspace{14mu} {{No}.}} \\{{of}\mspace{14mu} {Substituted}}\end{matrix} \\{{Hydroxy}\mspace{14mu} {Group}}\end{matrix}\mspace{31mu}}{\begin{matrix}{{Total}\mspace{14mu} {{No}.\mspace{14mu} {of}}\mspace{14mu} {Hydroxy}} \\{{Group}\mspace{14mu} {in}\mspace{14mu} {Cycodextrin}}\end{matrix}\mspace{14mu}} \right) \times 100 ( \% )}}\;} & {{Equation}\mspace{14mu} 1}\end{matrix}$

In the Formula 4, a, b, c, d and e are each an integer having a value ofat least 0, where the sum of a+b+c+d+e is at least 1. That is to say,the linking order of the constituent units a, b, c, d and e is notlimited to the Formula 4, but may be randomly changed. The hydrocarbonfunctional group represented by Formula 4 may include, but is notlimited to, methyl, ethyl, butyl, octyl, decyl, hexadecyl, aryl, phenyl,benzyl, etc.

In the Formula 5, R₁, R₂ and R₃ are each independently a hydrocarbonfunctional group having 1 to 20 carbon atoms represented by Formula 4.The silane functional group represented by Formula 5 may include, but isnot limited to, trimethyl silane, butyldimethyl silane, methoxy silane,ethoxy silane, methacryloxypropyl methoxy silane, etc.

Such cyclodextrin derivatives may be manufactured by reacting thecyclodextrin represented by the Formula 2 with the compound representedby the following Formula 6.

R—X  Formula 6

In the Formula 6, R is identical to the substituent “R” of the Formula3, and X is a functional group that may react with a hydroxy group ofthe cyclodextrin represented by Formula 2, and may include, for example,halogen, a hydroxy group, an alkoxy group, etc. A hydrogen atom in thehydroxy group of the cyclodextrin is substituted with a substituent “R”by means of the above-mentioned substitution reaction. A degree in whichthe hydrogen atom is substituted with a substituent “R”, namely asubstitution degree of the substituent “R” may be adjusted according toa mole ratio of the added compound represented by the Formula 6 duringthe substitution reaction.

Subsequently, the prepared cyclodextrin derivatives, PVC and a lowmolecular weight liquid plasticizer are mixed to form a plastisol (S2).

Contrary to the pure cyclodextrin of the Formula 2, the cyclodextrinderivatives of the Formula 3, in which the hydrogen functional group issubstituted with a predetermined compound, have a good dispersibilitywhen they are mixed with the PVC and the low molecular weight liquidplasticizer. Accordingly, the plastisol, in which the cyclodextrinderivatives are homogeneously dispersed, may be formed without using aconventional solvent such as DMAc. Therefore, the flexible PVC withsuppression of the migration of a plasticizer may be mass-produced in asimple and economic manner.

An amount of the mixed cyclodextrin derivatives preferably ranges from 2to 20 mol, based on 100 mol of the low molecular weight liquidplasticizer.

Also, all plasticizers may be used as the low molecular weight liquidplasticizer if the plasticizers can form a complex in cavities of thecyclodextrin derivatives. Considering cavity sizes of the cyclodextrinderivatives, the used plasticizer may include, but is not limited to,conventional low molecular weight liquid plasticizers used for softeningPVC, for example phthalate plasticizers such as dimethyl phthalate(DMP), dibutyl phthalate (DBP), di-isobutyl phthalate (DIBP), dihexylphthalate (DHP), dioctyl phthalate (DOP), di-iso-octyl phthalate (DIOP),dinonyl phthalate (DNP), di-isodecyl phthalate (DIDP), benzyl butylphthalate (BBP), etc.; aliphatic diester plasticizers such as dioctyladipate (DOA), di-iso-octyl adipate (DIOA), di-isodecyl adipate (DIDA),etc.; trimellitate plasticizers such as tri-iso-octyl trimellitate(TIOTM), etc.; and phosphate plasticizers such as tritolyl phosphate(TTP), trixylyl phosphate (TXP), etc., and they are used alone or incombinations thereof. It is apparent to those skilled in the art that amixed ratio of the low molecular weight liquid plasticizer to the PVCmay be varied according to the desired softening degree of PVC products,and, for example, 10˜80 parts by weight of the plasticizer is preferablymixed, based on 100 parts by weight of the PVC.

In the above-mentioned step S2, a plastisol may formed by mixing thecyclodextrin derivatives together with PVC and a low molecular weightliquid plasticizer, but a plastisol may formed by first mixing thecyclodextrin derivatives with a low molecular weight liquid plasticizerto form a plasticizer composition, followed by mixing the plasticizercomposition with PVC. That is to say, a plasticizer compositionincluding cyclodextrin derivatives and a low molecular weight liquidplasticizer may be first prepared according to the present invention,and then used instead of the conventional plasticizers of the PVC.

Finally, the resultant plastisol is heated to form a solution, and thenthe solution is cooled (S3).

When the plastisol, which is formed by adding the cyclodextrinderivatives of Formula 3 to the flexible PVC composition including PVCand a low molecular weight liquid plasticizer, is heated, for example,to about 180° C., the plastisol is changed to a phase of solution inwhich other components are dissolved with the low molecular weightliquid plasticizer, and, when the solution is then cooled, a flexiblePVC composition with suppression of the migration of a plasticizer, inwhich all components of the PVC, the low molecular weight liquidplasticizer and the cyclodextrin derivatives are mixed homogeneously, ismanufactured.

In the manufactured flexible PVC composition with suppression of themigration of a plasticizer, a principle of suppressing the migration ofa plasticizer is described in brief, as follows.

FIG. 1 is a schematic diagram showing a structure of α-cyclodextrinderivatives as one example of cyclodextrin derivatives used in thepresent invention. Referring to FIG. 1, α-cyclodextrin derivatives arestructures having a cavity formed therein. Such cyclodextrin derivativesprevents the plasticizer from flowing out of the PVC products since thecyclodextrin derivatives attracts the low molecular weight liquidplasticizer, for example DOP, into their cavity to form a complex (seeFIG. 2). That is to say, the flexible PVC composition with suppressionof the migration of a plasticizer according to the present invention, inwhich the PVC, the low molecular weight liquid plasticizer and thecyclodextrin derivatives are mixed homogeneously as shown in FIG. 3, hasan improved effect on the suppression of the migration of theplasticizer, and also maintains physical properties without loss oftheir efficiency since the cyclodextrin derivatives effectively form acomplex with DOP.

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.However, the description proposed herein is just a preferable examplefor the purpose of illustrations only, not intended to limit the scopeof the invention, so it should be understood that other equivalents andmodifications could be made thereto without departing from the spiritand scope of the invention. The preferred embodiments of the presentinvention will be described in detail for the purpose of betterunderstandings, as apparent to persons by persons who have ordinaryskill in the art.

Synthetic Example 1

In this Synthetic example, β-cyclodextrin was reacted with benzylchloride to synthesize cyclodextrin derivatives represented by thefollowing Formula 7.

The synthesis of 2,3,6-tri-O-benzyl-β-cyclodextrin (hereinafter,referred to as “Bn-β-CD”), represented by Formula 7, was carried outaccording to the method disclosed in the literature [CarbohydrateResearch 1990, Vol. 199, P. 31-35 “Synthesis of1,4-anhydro-2,3,6-tri-O-benzyl-α-D-glucopyranose by cis-ring-closure ofa glycosyl chloride”].

The β-cyclodextrin used in the reaction was purchased from Tokyo Kasei.5.0 g of the β-cyclodextrin was dissolved in 250 ml ofdimethylsulfoxide. Then, 3 g of sodium hydride (NaH) was evenlydispersed in 50 ml of DMSO, and then the resultant mixture was added tothe previously prepared β-cyclodextrin solution and stirred at 21° C.Subsequently, 14 ml of benzyl chloride was slowly added to the stirredmixture for 6 hours, and then a precipitate was obtained using water.The precipitate was added in acetone, and then impurities were removedfrom the precipitate and the impurities-free precipitate was dried toobtain a product containing Bn-β-CD. The dissolution and precipitationprocesses were repeated using acetone and methanol to obtain a morepurified product.

The Bn-β-CD product obtained through the processes was analyzed forcontents of carbon, hydrogen, oxygen atoms to calculate a weight ratioof each of the atoms. And, the results are listed in the following Table1.

On the basis of the results, it was determined how much hydrogen in theterminal hydroxy functional group of the β-cyclodextrin is substituted.As s result, it was revealed that 19 (about 90.5%) of the total 21functional groups of the β-cyclodextrin are substituted with benzylchloride during the substitution reaction.

TABLE 1 Atoms Carbon Hydrogen Oxygen % by weight 72.1917 6.3808 19.2859

Synthetic Example 2

In this synthetic example, the β-cyclodextrin was reacted with3-trimethoxysilylpropylmethacrylate represented by the following Formula8 to synthesize cyclodextrin derivatives represented by the followingFormula 9.

The synthesis of the above cyclodextrin derivatives of Formula 9 wascarried out, as follows. Before a modification process of theβ-cyclodextrin, moisture was completely removed from the β-cyclodextrinusing a Dean-Stock apparatus. 250 ml of N,N-dimethylformamide was addedto a 3-neck flask equipped with a reflux tube and a nitrogen inlet, andthen 15 g of β-cyclodextrin was also added the flask. The resultantmixture was completely dissolved while stirring. And, the inside of the3-neck flask was then brought to a vacuum state, and then nitrogen and15 ml of 3-trimethoxysilylpropylmethacrylate were added sequentially tothe 3-neck flask, and reacted for 48 hours at a constant temperature of80 to 100° C. Subsequently, dimethylformamide was removed by passing thereaction solution through the column, and a precipitate was obtainedusing acetone, and then dried for a day under a vacuum condition.

Examples

In these Examples, the cyclodextrin derivatives synthesized in theSynthetic example 1 were used to prepare flexible PVC compositions withsuppression of the migration of a plasticizer.

Commercially available PVC (LG Chemicals Ltd., LP170) was used as thePVC, and dioctyl phthalate (hereinafter, referred to as “DOP”), which isone of the typical low molecular weight liquid plasticizers, was used asthe plasticizer. SDB CIZER-E03 (ShinDongBang Corp.) was used asepoxidized soybean oil known as the secondary plasticizer, and MT-800(Songwon Industrial Co., Ltd.) was used as the heat stabilizer.

Firstly, PVC, DOP, and the cyclodextrin derivatives obtained in theSynthetic example 1 were added with a secondary plasticizer and a heatstabilizer as other additives to a container, based on their contents aslisted in the following Table 2, and mechanically stirred for 24 hoursto form a plastisol. In the Table 2, the contents are represented by apart(s) by weight.

TABLE 2 Secondary Heat Cyclodextrin No. PVC DOP Plasticizer StabilizerDerivatives Total Comparative PVC-0 100.00 57.00 3.00 2.00 — 162.00example 1 Example 1 PVC-1 100.00 57.00 3.00 2.00 1.63 163.63 Example 2PVC-3 100.00 57.00 3.00 2.00 5.01 167.01 Example 3 PVC-6 100.00 57.003.00 2.00 10.34 172.34 Example 4 PVC-9 100.00 57.00 3.00 2.00 16.02178.02

The resultant plastisol was aged for about 2 weeks in a vacuum oven, andthen a suitable amount of the plastisol was added to a mold and theplastisol-containing mold was put into a processing oven, heated at atemperature of 180° C. for about 5 to 10 minutes until it is in asolution phase, and then kept at a room temperature to prepare flexiblePVC samples with suppression of the migration of a plasticizer.

The contents of the cyclodextrin derivatives to the total content of theplastisol were represented by percent (%) by weight, and the numbers ofthe prepared samples were marked according to the contents of the usedcyclodextrin derivatives. For example, if flexible PVC samples areprepared, respectively, from plastisols containing 0, 1, 3, 6 and 9% byweight of cyclodextrin derivatives, the flexible PVC samples are namedPVC-0, PVC-1, PVC-3, PVC-6 and PVC-9, respectively.

Dispersibility Evaluation of Cyclodextrin Derivatives

FIGS. 4 and 5 are photographs taken of surfaces of a cyclodextrinderivatives-free sample (PVC-0) of Comparative example 1 and a sample(PVC-9) of Example 4 containing a small amount of the cyclodextrinderivatives. Also, FIG. 6 is a photograph taken of a surface of a sampleobtained by dispersing pure β-cyclodextrin in a DMAc solvent.

As shown in FIG. 6, it was determined whether the cohesion, which ispointed out as the problem caused in the manufacturing method of theflexible PVC with suppression of the migration of a plasticizer in theuse of the pure β-cyclodextrin, appears in the flexible PVC using thecyclodextrin derivatives according to the present invention. As shown inthe photographs, it was revealed that a surface of the PVC-9 is notnearly different to that of the PVC-0, indicating that the cyclodextrinderivatives are homogeneously dispersed without their cohesion.

Migration Evaluation of Plasticizer

The prepared flexible PVC samples were tested for the migration of aplasticizer using a method as described just later. The migration testwas carried out according to a modified method ISO (InternationalStandard Organization) 3826 “Plastics collapsible containers for humanblood and blood components”, which is suitably adapted to thisapplication.

First, in order to determine DOP concentration, various concentrationsof standard DOP solutions were prepared according to a procedure asdescribed just later, and a calibration curve was plotted by measuringabsorbance of the standard DOP solutions at a wavelength of 272 nm usinga UV-vis spectrophotometer.

The standard DOP solutions were prepared at contents of 1, 2, 5, 10 and20 mg of DOP, respectively, based on 100 ml of a mixed ethylalcohol/water solution used in the DOP migration test, and theirmanufacturing method is described in detail, as follows.

The DOP migration solution was prepared by suitably mixing ethyl alcoholand water until a density of the mixed ethyl alcohol/water solution was0.9373˜0.9378 g/ml. At this time, the used ethyl alcohol has a purity of95.1˜96.6% (v/v) and a density of 0.8050˜0.8123 g/ml. 1 g of DOP wasadded to ethyl alcohol and the resultant mixture was adjusted with themigration solution to a final volume of 100 ml. Then, 10 ml of theresultant solution was re-diluted with the migration solution to theentire volume of 100 ml. The re-diluted solution was taken,respectively, in aliquots of 1, 2, 5, 10 and 20 ml, and re-diluted withthe migration solution to the entire volume of 100 ml. The aboveprocedures were repeated to prepare standard solutions having a DOPconcentration of 1, 2, 5, 10 and 20 mg/100 ml, respectively.

The standard solutions prepared thus were measured for their absorbancesat a wavelength of 272 nm using a UV-vis spectrophotometer, and then acalibration curve of the standard solutions was plotted using theirabsorbances, as shown in FIG. 7. It was found that the plottedcalibration curve fully complied with a Beer-Lambert equation, and theconcentrations of the samples may be calculated from the absorbances ofthe samples. A Beer-Lambert equation is represented as shown in thefollowing Equation 2.

$\begin{matrix}{{Absorbance} = {{\log\left( \frac{\begin{matrix}{{{Intensity}\mspace{14mu} {of}\mspace{14mu} {Light}}\mspace{14mu}} \\{{Penetrating}\mspace{14mu} {into}\mspace{14mu} {Sample}}\end{matrix}}{\begin{matrix}\begin{matrix}{{{Intensity}\mspace{14mu} {of}\mspace{14mu} {Light}}\mspace{14mu}} \\{{Penetrating}\mspace{14mu} {out}}\end{matrix} \\{{through}\mspace{14mu} {Sample}}\end{matrix}\mspace{14mu}} \right)}\mspace{130mu} = {{Molar}\mspace{20mu} {Extinction}\mspace{14mu} {Coefficient} \times {Concentration} \times {Light}\text{-}{Penetration}\mspace{14mu} {Length}}}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

The previously manufactured flexible PVC samples were added to 100 g ofmigration test solutions and sealed, respectively, and then kept at aconstant ambient temperature of 37±1° C. And, absorbances of themigrated solutions was measured at a wavelength of 272 nm everypredetermined time point using a UV-vis spectrophotometer, andconcentrations of DOPs migrated from the samples were calculated byassigning these absorbances to the previously plotted test curve. Theresults are listed in the following Table 3 and shown in FIG. 8. Unitsin the following Table 3 are defined in the terms of mg/100 ml.

TABLE 3 DOP concentration After No. After 6 hrs After 12 hrs After 24hrs After 48 hrs 72 hrs PVC-0 4.393 7.916 12.490 17.814 18.028 PVC-13.568 7.156 11.023 14.652 15.361 PVC-3 2.439 5.131 9.402 12.116 13.349PVC-6 2.360 4.782 8.063 11.512 12.519 PVC-9 1.819 3.760 6.758 9.94511.244

Referring to Table 3 and FIG. 8, it was revealed that the concentrationsof the migrated DOPs are decreased as the content of the cyclodextrinderivatives increases, namely as the sample numbers from PVC-0 to PVC-9increases, indicating that the cyclodextrin derivatives suppress themigration of the plasticizer DOP. In particular, it was revealed thateven a small amount of the cyclodextrin derivatives significantlyimprove an effect of suppressing the migration of a plasticizer,indicating that the cyclodextrin derivatives attract and fix a lowmolecular weight liquid plasticizer into the outer surface of the cavityby means of hydrogen bonds, in addition to attracting the low molecularweight liquid plasticizer into their cavities.

Physical Property Evaluation of Flexible PVC

This evaluation method was designed to determine an effect of theimpregnated cyclodextrin derivatives on mechanical properties of theflexible PVC.

In order to carry out a tensile test of the manufacture flexible PVC,dumbbell shapes of samples were first prepared using a sample cutter,and loads of the prepared samples were measured by elongating thesamples at a crosshead speed of 50 mm/min using a Lloyd LR10K universaltesting machine (UTM). Measured values of the stress and the strain atbreaks are listed in Table 4, and a stress-strain curve plotted from themeasured values is shown in FIG. 9.

TABLE 4 No. Stress (N/mm²) Strain (%) PVC-0 21.05 445.17 PVC-1 20.29436.65 PVC-3 20.01 433.81 PVC-6 19.83 440.78 PVC-9 17.44 418.40

Referring to Table 4 and FIG. 9, it was reveled that the stress and thestrain at breaks are slightly decreased as a concentration of thecyclodextrin derivative, Bn-β-CD, increases, and their total changes arevery slight within the range of 10%. From these results, it wasconfirmed that the mechanical properties of the flexible PVC containingthe cyclodextrin derivatives are hardly deteriorated.

INDUSTRIAL APPLICABILITY

As described above, the manufacturing method of the present inventionmay be useful to mass-produce the flexible PVC with suppression of themigration of a plasticizer in a simple and economic manner without theuse of solvents if the cyclodextrin derivatives substituted with apredetermined compound are used as a compound that can form a complexwith low molecular weight liquid plasticizers used for the flexible PVC.

Also, the manufactured flexible PVC has an improved effect ofsuppressing the migration of the plasticizer without deterioration inits mechanical properties by enabling the cyclodextrin derivatives toeffectively form a complex with DOP since the low molecular weightliquid plasticizer and the cyclodextrin derivatives are mixedhomogeneously with each other.

1. A method for manufacturing a flexible PVC composition withsuppression of the migration of a plasticizer, the method comprising:(S1) preparing cyclodextrin derivatives represented by the followingFormula 3; (S2) mixing the cyclodextrin derivatives, PVC and a lowmolecular weight liquid plasticizer to form a plastisol; and (S3)heating the formed plastisol to form a solution and cooling thesolution:

wherein, R is independently selected from the group consisting ofhydrogen, a hydrocarbon functional group having 1 to 20 carbon atomsrepresented by the following Formula 4, and a silane functional grouphaving 1 to 60 carbon atoms represented by the following Formula 5,where the substituent “R” has a substitution degree of 5 to 100%; and nis an integer from 6 to 26:

and wherein, a, b, c, d and e are each an integer having a value of atleast 0, where the sum of a+b+c+d+e is at least 1, and the linking orderof the constituent units a, b, c, d and e is randomly changed:

wherein, R₁, R₂ and R₃ are each independently a hydrocarbon functionalgroup having 1 to 20 carbon atoms represented by the Formula
 4. 2. Themethod for manufacturing a flexible PVC composition with suppression ofthe migration of a plasticizer according to claim 1, wherein thecyclodextrin derivatives have a content of 2 to 20 mol, based on 100 molof the low molecular weight liquid plasticizer.
 3. The method formanufacturing a flexible PVC composition with suppression of themigration of a plasticizer according to claim 1, wherein the lowmolecular weight liquid plasticizer is one selected from the groupconsisting of a phthalate plasticizer, an aliphatic diester plasticizer,a trimellitate plasticizer and a phosphate plasticizer.
 4. The methodfor manufacturing a flexible PVC composition with suppression of themigration of a plasticizer according to claim 3, wherein the phthalateplasticizer is one selected from the group consisting of dimethylphthalate (DMP), dibutyl phthalate (DBP), di-isobutyl phthalate (DIBP),dihexyl phthalate (DHP), dioctyl phthalate (DOP), di-iso-octyl phthalate(DIOP), dinonyl phthalate (DNP), di-isodecyl phthalate (DIDP), benzylbutyl phthalate (BBP) and mixtures thereof.
 5. The method formanufacturing a flexible PVC composition with suppression of themigration of a plasticizer according to claim 1, wherein the functionalgroup represented by Formula 4 is

and the functional group represented by Formula 5 is


6. A flexible PVC composition with suppression of the migration of aplasticizer comprising PVC and a low molecular weight liquidplasticizer, the flexible PVC composition further comprisingcyclodextrin derivatives represented by the following Formula 3:

wherein, R is independently selected from the group consisting ofhydrogen, a hydrocarbon functional group having 1 to 20 carbon atomsrepresented by the following Formula 4, and a silane functional grouphaving 1 to 60 carbon atoms represented by the following Formula 5,where the substituent “R” has a substitution degree of 5 to 100%; and nis an integer from 6 to 26:

and wherein, a, b, c, d and e are each an integer having a value of atleast 0, where the sum of a+b+c+d+e is at least 1, and the linking orderof the constituent units a, b, c, d and e is randomly changed:

wherein, R₁, R₂ and R₃ are each independently a hydrocarbon functionalgroup having 1 to 20 carbon atoms represented by the Formula
 4. 7. Theflexible PVC composition with suppression of the migration of aplasticizer according to claim 6, wherein the cyclodextrin derivativeshave a content of 2 to 20 mol, based on 100 mol of the low molecularweight liquid plasticizer.
 8. The flexible PVC composition withsuppression of the migration of a plasticizer according to claim 6,wherein the low molecular weight liquid plasticizer is one selected fromthe group consisting of a phthalate plasticizer, an aliphatic diesterplasticizer, a trimellitate plasticizer and a phosphate plasticizer. 9.The flexible PVC composition with suppression of the migration of aplasticizer according to claim 8, wherein the phthalate plasticizer isone selected from the group consisting of dimethyl phthalate (DMP),dibutyl phthalate (DBP), di-isobutyl phthalate (DIBP), dihexyl phthalate(DHP), dioctyl phthalate (DOP), di-iso-octyl phthalate (DIOP), dinonylphthalate (DNP), di-isodecyl phthalate (DIDP), benzyl butyl phthalate(BBP) and mixtures thereof.
 10. The flexible PVC composition withsuppression of the migration of a plasticizer according to claim 6,wherein the functional group represented by Formula 4

and the functional group represented by Formula 5


11. A plasticizer composition comprising a low molecular weight liquidplasticizer and cyclodextrin derivatives represented by the followingFormula 3:

wherein, R is independently selected from the group consisting ofhydrogen, a hydrocarbon functional group having 1 to 20 carbon atomsrepresented by the following Formula 4, and a silane functional grouphaving 1 to 60 carbon atoms represented by the following Formula 5,where the substituent “R” has a substitution degree of 5 to 100%; and nis an integer from 6 to 26:

and wherein, a, b, c, d and e are each an integer having a value of atleast 0, where the sum of a+b+c+d+e is at least 1, and the linking orderof the constituent units a, b, c, d and e is randomly changed:

wherein, R₁, R₂ and R₃ are each independently a hydrocarbon functionalgroup having 1 to 20 carbon atoms represented by the Formula
 4. 12. Theplasticizer composition according to claim 11, wherein the cyclodextrinderivatives have a content of 2 to 20 mol, based on 100 mol of the lowmolecular weight liquid plasticizer.